The two door arches are identical. The posts are solid, built up from 2 x
4 and 2 x 8 pieces (screwed together). I used some ½ ply to
increase the width to get the desired 4 x 4 cross section for the
post core, then clad the core with 1 x 5 VG fir, cut down to exactly
4. The 1 is nominal, and so required some ½ and Ύ plywood to
build the core up to meet it. The post's outer cross section is 6
square. 2 x 4s are actually 1 ½ x 3 ½, so I cut some ½
ply either side to build up the long dimension, and Ύ ply to build up
the short dimension.

If I did this again, Id probably save some work by using a 2 x 6
instead of a 2 x 4. Then Id only have to build up the thickness,
not the width.

Post from above

corners are 11/16th radius Ό round mouldings, which were glued
in place.

I wrapped the post in string and used shims to hold the mouldings in from
the outside at several places down the height.

The post caps are cut from 1 x 5, with the corners cut out and filled
with short sections of Ό round moulding. These were glued onto the top of
the posts. The quarter that is removed is aligned inward so that the roof
will sit between them.
The dashed part of the diagram to the left shows the position of the 2x8 cross bar
that forms the basis of the top of the arch. The protrusions stop at the
base of the cross bar.

The cross beam was made from a 2x8 (actually 1 ½ x 7 ½) beam, clad
with pieces as shown below: The tops and bottoms of the sign box are 4
wide. They protrude 1 infront of the posts, so I used a jigsaw to get
them to go accurately around the contour of the posts near their ends. The
decorative pieces beneath are 2 ½, 2 Ό and 2 wide as you go
down. These meet the doors, which are 1 1/2  thick and back onto the
centre line (dashed line down centre). The sign box is large enough for a
fluorescent light fitting.

Sign box ends

A view into the console room

The sign itself is a piece of acrylic sheet cut to size. I used Microsoft
Publisher to print the text onto a poster 42 wide. Here's a
PDF of the sign image.
Initially I printed this onto five sheets of paper and taped it behind the acrylic,
but I needed to improve this, as the joins show if it is backlit. I took
the "prototype" to a Sign-maker's shop. Dr Who not being that
well known in the US I had to explain what these were (in general terms so
that they didn't think I was completely mad...). They were able to
turn out four of the acrylic inserts (see left) in a couple of days for not even too much money.

The
interior of the sign box is routed to provide a groove for the acrylic
sign. I actually did the routing with the table saw, though a router would
do as well or better. The corners are mitred. I glued 4" squares of
½" plywood onto the edges of the sign box sides. These sit behind
the sign front and hold the sides on, which allows the sign front to slide
out sideways to enable access to the strip light behind.

The door arches are actually not really strong enough, even though I used
dowels, glue and big 3 screws to join the cross beam to the posts. The
posts are so heavy that moving the arches can twist the cross beam. To
prevent this, I nailed a 2x4 across the bottom of the posts when moving
the TARDIS.